Large liquid storage tanks, such as those used on fire engines, etc., have high strength requirements due to the weight of the liquid stored in the tank. Liquid storage tanks for fire engines, for example, can hold a thousand gallons or more of water and must obviously do so with a high reliability.
Such liquid storage tanks have been developed with side, bottom and top pieces welded together to form the tank. Side, bottom and top pieces are shown in FIGS. 1 and 2. These pieces were hand welded together by a traditional weld, such as the triple weld shown in FIGS. 2, 3a and 3b, or by the tri-rod weld shown in FIG. 4. In the triple weld of FIGS. 2, 3a and 3b, a side piece 10 and a bottom piece 12, for example, were welded together by a hot tip hand welder guided along the side-bottom seam while " width side 10 and bottom 12 pieces. The welder melted the welding rods 20 and applied them to the interior corner junction between the side piece 10 and the bottom 12. Three such welding rods 20 (FIG. 3b) were placed overlapping each other in the manner shown in FIG. 3a to form the weld 15.
As shown in FIG. 2, the triple welds 15 were used in the junctions formed between the abutting sides 20 and bottom 12. The welds 15 were also used in the junctions formed between the abutting sides 20 and top 14.
An alternative to the triple welds was the triangular rod weld 22, shown in FIG. 4. In the triangular weld embodiment, the side piece 10 was welded to the bottom piece 12 by a triangular welding rod 22 by pushing the rod 22 into the hot tip hand welder as the operator guided the hand welder along the side-bottom or side-top seam.
The triple weld 15 and the triangular rod weld 22 could hold the sides, bottom and top pieces together under the force of the water weight. But, improvements in strength are always desirable in order to increase tank capacities and to reduce material costs.